Re: C Programming

johnoaxl (slong@interchange.ubc.ca) Sat, 02 Dec 2000 00:10:36 -0800 

Date: Sat, 02 Dec 2000 00:10:36 -0800
From: johnoaxl <slong@interchange.ubc.ca>
Subject: Re: C Programming



William,

for your interest, you could use the following FOR loop statement to
elimate the 16 IF statements.

      for ( i=0; i < BITSHIFT; i++)
         {
                for ( n=0; n < BITSHIFT; n++ )
                  {
                         spoke ( DPORT, C << i );
                         if ( speek(DPORT) & R << n )
                            {
                                 j = i + 4*n ;
                            }
                  }
         }

This method will always start scaning/checking each number from column 1
row 1, row 2, row 4, and row 8, then shift to column 2 and check the
number in each row and so on until the number matches up with the
corresponding button pressed.  It then returns a value j which is the
number of the button pressed.  Say, if you pressed 4, j will give 4.
Although this method would save you some typing, it actually takes
longer time to find the match of the button pressed.  So, i suggest to
stick with your 16 IF statements for later use, say for Lab 3.


Seng Ong